The present invention relates to an apparatus for electrochemical marking of a metallic surface of a workpiece.
In an apparatus, known from DE 27 28 256 C3, for electrochemical marking of a metallic surface which is connected to one pole of a voltage source and which has a tool provided with at least one metallic pin connected with the other pole of the voltage source, a tool holder of an electrically non-conducting material which holds the pin or pins, and a liquid electrolyte placed between the tool and the workpiece surface, the tool holder is provided with a centered cutout at its underside, which is flat in this area, within which the tool in the pins are held, where the front ends of the pins are located in a common plane with the base surface of the cutout. Accordingly, during the marking operation the tool holder rests with the area of its underside surrounding the cutout on the metallic surface of the workpiece to be marked. The electrolyte is inserted from the outside into the space, formed by the cutout, between the marking pins of the tool and the surface of the workpiece to be marked.
Because the tool holder slides with a more or less extensive surface of its underside on the surface of the workpiece to be marked, abrasion marks on the surface of the workpiece to be marked cannot be avoided, for one, and secondly, wear of this sliding surface area of the tool holder also occurs. The latter results in the space between the tool and the surface to be marked becoming narrower, which has a disadvantageous effect on the quality of the marking. It would be possible to avoid the danger of wear of the tool holder by the use of appropriate wear-resistant plastic materials, but as a rule these plastic materials contain halogen, which is not permissible for marking of certain workpieces, for example zirconium pipes such as are used for fuel elements of reactors. A further disadvantage lies in the disadvantageous and expensive separate provision of the electrolyte used for electrochemical marking.